still running bad.

[T77911S]

gonna start all over.
i just got my WUR back from brian so i am running his pressures and since gauges and LM are at my brothers, i had to set mixture buy ear. but it is running pretty rich at idle.

symptoms:
runs bad at cruise/steady speeds. the car has a slight buck and i can feel the engine vibrating thru the body. its like it is off balance. cant say i really hear a miss, just more of the vibration and bucking.
idle seems good, or jsut not noticeable. on boost seems fine. it seems to smooth out when accelerating.
previously it was running very lean at cruise/steady speeds. like in the low 16's.
if there is an air leak it would be where the IC sits on the throttle body. it goes on, but it rocks a little.

here is what is on the car:

original pressures:
46k miles

cold 54 degrees- 1.4bar
hot- 3.9bar
system- 6.2bar

current pressures not known.

no O2 sensor
no freq valve
injectors- 009
WUR-054
FD- 037 with large fuel lines.
AFM- 205?
header- ?
dual out exhaust- BORLA
RUF intercooler
K27- 7006
WG- tial .9bar
dist- 02378045 (maybe 0237302045)


compression- 120 left side 130 rt.
cam timing the same for each side
leakdown- 4%
fuel flow out of FD/no injectors- 3 at 5.3 oz's. low was 5.1 hi 5.6
fuel flow W/injectors- no weights yet but it looks better than previous
fuel flow. 1.9 liters per 30 sec
spray pattern- not checked
swapped ignition wires with old set with better resistance. now have new wires.
cap- cleaned now new
rotor- new
coil- new MSD
CD- MSD 6AL
plugs- new
timing- 26 degrees
advance works
retard works
valves adjusted

i may go back and do the valves again. i found #4 in loose yesterday.

what about something unbalancing the engine? flywheel/clutch or even something in the tranny.

i tried to start it on jack stands when it was in gear. the engine turned over very rough with a knocking sound. at first i thought something fell into the motor but then i found it was just in gear. it only did this with the plugs in.. i pulled the plugs and it spun over fine while in gear. (it was not in gear on purpose).

i am pretty much at the end. the only things i have not really done is had the dist curve tested adn the FD and injectors checked. i did check them for fuel volume and they were all pretty close.

it does sometimes blow smoke at startup. seems like it happens if i dont let it ilde long enough before shut down. it was supposedly re-ringed ebfore i got it but i doubt the tech. it does not look like things were cleaned up like they should have been. heads are still very dirty from old oil leaks, jsut things like that.

[fraggle]

Subscriber so I can learn more.... Hopefully someone with more knowledge than me will reply.

[klefroid]

Are you shore that you are running on all 6 cylinders?
when you unplug one ignition wire each time with the engine running idle you should hear if one is not working.

[speednme1]

I know this may sound silly but from your list I did not see that you have checked your grounding strap..if loose it can cause all sorts of weird things.

[T77911S]

Originally Posted by timc

curious as well on solution to this problem, as this will separate the men from the boys....(btw, i am a boy!)

check you AFR's under boost before we put in your 1bar. then we can check it again after on saturday after. i will also bring down the leak down tester and get some numbers on your motor.

[JFairman]

Have you removed all 6 sparkplugs and looked to see they are all about the same middle grey or tan color?

[T77911S]

i have looked at several sets of plugs now and i cant tell if one is running or richer or leaner.
i will pull them again next time i have it down to that point.

the ground wire is there but i was never concerned about it before because i had the MSD grounded to the engine. now it is grounded on the plate that the bosch unit mounted on so i need to check that.

i was running very rich. i leaned it out on the way home and it seemed to run better. then later when i drove it it seemed a little worse. kind of how this has been going all along. make a change and it seems better then later it is not. although now i think i have it one "bump" too lean. gonna go back one richer.

i am going to look into the grounds some more. may even run another ground form the MSD to the engine.

[jwasbury]

Originally Posted by klefroid

Are you shore that you are running on all 6 cylinders?
when you unplug one ignition wire each time with the engine running idle you should hear if one is not working.

i'd verify firing order - easy to screw up (I've done it) and surprising how well the car will run with a couple cylinders off timing.

Also, can you tell us what your ignition timing is at idle? You say 26 degrees is max advance (assume at 4000rpm, vac hose connected or disconnected?). If I were futzing around with that car, I'd try backing the ignition timing off a few degrees, see how it runs then. Easy to do, nothing to lose in trying.

[T77911S]

the ignition wires is a funny thing. i bought the clewet(?) wires. they put numbers on the ends that go in the cap. hey guys, thats not where they are needed! they need to be on the plug end. i wrote on the end of each one th eplug number because trying to trace one back is a pain.

timing is a good concern. it is really about all thats left.
there were washers under the vacc pot when i got the car. i dont know why. i have removed them. also, my timing at idle is very hi. vac retard is removed right now. i would say it is around 18BTDC with no retard. i am going to looks at timc's this weekend to see what his is doing.
i have read that boost has no effect on the retard side of the vacuum pot, only the vacuu advance in that it retards the timing under boost.
my testing shows otherwise.. i ran both sides of the vac pot to a T then put about 10psi to the hose. timing did not move. so for safety sake, i have the vac retard line removed for now.
it would make sense that they could put a valve in there that let boost out of the retard side. instead i think they used those vacuum solenoids to block boost. maybe the pots are different for US,ROW and even the early cars.

[T77911S]

here is what it was doing yesterday.

it sounded exactly like a plug that was not firing but was on the edge of firing or one that was firing part time. i think this is a lean miss fire but will have to verify on saturday. this is what it was doing before.


i have run it without the vac advance and had been thinking of retarding the timing, so i just did that. have not driven it yet.

[RarlyL8]

I did not see all the diagnostic work you have done; did you pull the injectors and verify all 6 were delivering spec fuel volume?

[mooney265]

Originally Posted by T77911S

here is what it was doing yesterday.

it sounded exactly like a plug that was not firing but was on the edge of firing or one that was firing part time. i think this is a lean miss fire but will have to verify on saturday. this is what it was doing before.


i have run it without the vac advance and had been thinking of retarding the timing, so i just did that. have not driven it yet.

I once had 5 cylinders firing. turned out to be a dimpled diaphram on my fuel head. Causing excessive fuel in a single cylinder. I noticed it right away and put a IR-Temp on each exhaust port [header] and noticed one was remaining cold.

Rebuilt Fuel Head and good-to-go. Not sure if this helps, but thought i'd throw it out there...

[fredmeister]

Pull the plugs and look them over. Then run the plug gap down to 0.028 or so.....MSD suggests .040 but I found that my plugs were blowing out badly at high boost with this gap. This doesn't effect your idle or cruise issue but worth noting.

Then you need to see what your AF ratio is at idle and also your timing. You mentioned an MSD box but which one are you running---the 6AL2 programmable or what.
NOTE: MSD likes a special rotor without the internal resistor---- NAPA #EP407 if you can find one.

Let us know and maybe more ideas to follow.

Hang in there, I am fighting a very similar problem since going over to MSD fully programmable 6AL2 and adjustable WUR and its driving me insane. Though this sh$t aint gonna beat me.

Fred

[T77911S]

Originally Posted by RarlyL8

I did not see all the diagnostic work you have done; did you pull the injectors and verify all 6 were delivering spec fuel volume?

yes, i wanted to get my pressures back to spec. i should not have to drop my WCP as much as i was to get it to run right.
i just compared the volume of each to each other. i checked the fuel flow out of the head AND at the injectors. with the injectors on, it was better.
is there a spec for volume per minute or 30 seconds? (009 injectors)


i retarded the timing yesterday. ran like crap. barely drivable.
so i went the other way. advanced. it was a much better drive in this morning.
i was cruising along when i realized it was not bucking. although it was back a little when i dropped it down a gear and brought the RPM's up higher, but still better.
when i got the car, the timing was around 29degrees. when dropped it back to 26 degrees that may explain why it is running worse than when i got it. it could also explain the washers under the vac pot. someone was trying to get more advance at cruise. but it still does not explain it being so lean at cruise. (still need to check again).
i know the vac advance works. i can see it moving. plus, if i check the timing with the vac connected it is differrent than with it not connected.
with this being a euro system, should i be setting it to eruo timing?
what about the vac pots for US and ROW. are they different?

brian, if i have to run 29 degrees, can i drop the boost pressure to help?

[jwasbury]

be careful!

with all the mods that car has you really have no idea what distributor is on it or if it is original to the car (could be Euro, could be from an earlier US car). One thing you can be sure of is that too much advance kills. I've seen it kill an N/A 911 engine, and it kills even faster on a forced induction engine. could be worth while to send your dizzy off to a rebuilder with the proper equipment and make sure its functioning 100%.

1983 911 SC piston killed by too much ignition advance. My buddy said he loved the way the car was running with all that advance...until it started puking oil out of the tailpipe:


Remember that an ignition misfire will present as lean condition on the AFR gauge.

[T77911S]

here is my timing.

vac retard line is NOT connected.

at idle: timing is about 15BTDC
full advance, no vac lines connected: 26 degrees
vac advance: adds about 13 degrees
retard: takes out about 10 degrees.
dist is full CW to get 26 degrees

timing is not stable. i have not had this problem before. when i was checking the advance, it was jumping around. going to check wiring tonight and maybe do another valve adjust.

i looked in the shop manual for timing. that was no help. 2 specs were ATDC for US.
one diagram for the vac advance had the timing going from 20 to 0, unless i just read it wrong.

[jwasbury]

Originally Posted by T77911S

here is my timing.

vac retard line is NOT connected.

at idle: timing is about 15BTDC
full advance, no vac lines connected: 26 degrees
vac advance: adds about 13 degrees
retard: takes out about 10 degrees.
dist is full CW to get 26 degrees

timing is not stable. i have not had this problem before. when i was checking the advance, it was jumping around. going to check wiring tonight and maybe do another valve adjust.

i looked in the shop manual for timing. that was no help. 2 specs were ATDC for US.
one diagram for the vac advance had the timing going from 20 to 0, unless i just read it wrong.

Good luck making sense of the timing control diagrams in the factory workshop manual. The idle or max advance settings are helpful...IF you are certain what distributor you are dealing with. Are you certain that your distributor has vacuum advance? I believe many of the turbo models distributors do not. IIRC, on mine ('79 USA model) the vacuum pod only would retard timing. The pod had two inputs, one responded to vacuum (not boost), the other responded to boost (not vacuum). However, the pod only rotated the guts of the dizzy in one direction = counter clockwise, which retards the timing. The only advance mechanism on the distributor was centrifugal. The timing also "advances" in relative terms when there is no vacuum or boost pressure acting on the pod.

Who knows, maybe you've got a Euro dizzy there. In the workshop manual, you'll notice that for certain models you set the timing with the hoses disconnected, and other models you leave them connected. My '79 USA model the timing was set at idle with the vac hose connected...10 ATDC is the factory spec.

[T77911S]

update:
i thought some of the "new" problems were created by me and they were.
ALL the intake bolts were very lose. i had to go thru them about 8 times to get them tight.
bad thing is, the miss is still there BUT the "on boost" is better. seems to have quicker response.
bad news, theyare lose again.
when i first strated it after tightening the bolts, the idle was VERY low. funny thing is it seemed like i had to richen it up??? seemed odd.
question is, could i damage the intake gaskets kinda like blowing a head gasket?
next question, whats the trick to keeping them tight?
i think the long thin studs twist when torquing then untwist and loosen.
i had checked the intake bolts before i had removed the intake and they all were tight.
(i pulled the intake to have it powder coated)

the distributor:
i pulled it out. the vac retard pot moves it about a half a post width.
the boost retard moves it the same.
the vac advance moves about twice as much as the retard.
applying pressure to BOTH pots does NOT move the timing.

i did another leakdown on all but #1. 0% leakdown.
i did a compression test on 3, 120 psi.

all the plugs where extremely black except the ground strap and center electrode. porcelain was grey and electrode was clean. ( very long idle shut down)

[klefroid]

test for leaks, I use pilot spray , use a bit around the intakes and vacuum, when you hear a change in RPM you probably have a leak somewhere. Be careful

[T77911S]

retorqued the intake bolts with some blue loctite. probably should not have done that. now i cant tell if the studs losen up.
i am really frustrated now.
put the oscope on the signal to the coil. man i hate digital Oscopes but thats all i have at home.
the best i could see the signal looked fine. 3 pulses. maybe some jitter at the bottom but hard to tell with this scope.
i checked the output of the dist again. nice and clean. i will post a pic later. for those going MSD, you need to connect the violet to the "ground" from the dist.
i have the same roughness at idle as i do cruising.

i want to drive it to NC this weekend but listening to that motor might just be too aggravating to put up with.